The application of electrical and ultrasonic energy in the form of impulses to stimulate or monitor the progress of medical therapy or physical rehabilitation are old and well known techniques. Basically, these techniques rely on the use of at least one transducer means applied to a surface, such as electrodes for applying electrical impulses and a sound transducer for applying ultrasonic impulses.
The surface to which the transducer may be applied may be the skin of an animal or human or the transducer element may be applied to the surface of an article for non-destructive testing purposes.
In the application of electrical impulses to the skin of an animal or person, the amperage which is applied is varying quantities can produce considerable differences in the muscular action generated by the electrical current. Since the skin has some resistance, the currents generated by the electrodes may irritate the skin. Generally, it is necessary to use a covering on the electrode, particularly if the galvanic action is intended for the deeper tissues. It is now accepted practice that unless a definite type of action is desired from a bare metal electrode, such as an electrolysis or metallic ionization, a galvanic current should preferably be applied with covered electrodes. This avoids the very painful irritation and burns which usually result, even when a moderately intense current is employed with bare electrodes.
Where electrical currents are used medically for various therapuetic applications, it is preferred that bare metal electrodes not be used on the surface of the body. For example, it has been observed that when such electrodes have been used, electrolytic decomposition occurs under the metal. Moreover, there is a considerable risk of burning due to the presence of acid or caustic or by electrical action.
If it is essential that low-tension currents be used, then the metal electrodes are conventionally covered with gauze or other adsorbent material in sufficient width to overlap the edges of the metal. These pads are used for galvanic faradicsinusoidal treatments. The pad on these electrodes is usually soaked with a saline solution which serves to soften the skin and ease the current. It also diffuses the electrolytic decomposition products and tends to prevent chemical burns. The burns caused by improper contact with too thinly coated metal electrodes or bare metal electrodes can be quite severe, resulting in blisters which in turn lead to secondary infection which heals slowly and which can be very painful.
One of the more important area which is amenable to treatment by the use of electrical stimulation is that involving denervated muscle. The stimulation retards the progression of atrophy. Usually, it may be necessary to have several stimulation sessions a day to retard the atrophy.
This desirably would be facilitated if the electrodes stay in contact with the afflicted area for a long period of time without constant removal or reimplacement. Even those electrode contact media which are presently commercially available do not permit the use of bare electrodes. They must be used in combination with gauze covering of the electrode. Furthermore, the gels which are commercially available have the disadvantage of tending to liquify under the influence of the ingredients in human perspiration, such as body salts.
Applications in which burned skin is a particular problem using prior art techniques is in electro-shock therapy and in the defribilation of hearts.
In summary, the areas of use may include electrical monitoring of the heart (for example, EKG), physiological stimulation and the like. The application of ultrasonic impulses may similarly be used for stimulation or as a diagnostic tool in non-destructive testing.